1. Field of the Invention
The present invention relates to an apparatus and method for fabricating a liquid crystal display panel, and more particularly, to an apparatus and method for fabricating a liquid crystal display panel in which a defective unit liquid crystal display panel is discarded so that follow-up processes are not performed on the defective unit liquid crystal display panel when a single mode that liquid crystal display panels are fabricated with the same size on a large glass substrate, and in case of a multi-mode that liquid crystal display panels are fabricated with different sizes, sub-models are kept to proceed with a follow-up process.
2. Discussion of the Related Art
In general, a liquid crystal display device displays a desired image by individually supplying a data signal according to image information to liquid crystal cells arranged in a matrix form and controlling a light transmittance of the liquid crystal cells.
An improvement of yield in manufacturing liquid crystal display devices may be obtained by forming a plurality of thin film transistor array substrates on a large mother substrate and a plurality of color filter substrates on a separate mother substrate. The mother substrates are then attached. A plurality of unit liquid crystal display panels are formed from the attached thin film transistor array substrates and the color filter substrates and separated by cutting.
Usually, cutting of the unit liquid crystal display panels is performed such that a predetermined cutting line is formed on the surface of the mother substrate by using a wheel with a stronger hardness compared to a glass and propagating a crack along the cutting predetermined line.
The liquid crystal display panel will now be described with reference to the accompanying drawings.
FIG. 1 is an exemplary view illustrating a section of a plurality of unit liquid crystal display panels formed by attaching a first mother substrate with a plurality of thin film transistor array substrates formed thereon and a second mother substrate with color filter substrates formed thereon.
With reference to FIG. 1, in the unit liquid crystal display panels, the thin film transistor array substrates 1 protrude to one side compared to the color filter substrates 2, because a gate pad unit (not shown) and a data pad unit (not shown) are formed at the marginal portion of the thin film transistor array substrate 1 that does not overlap with the color filter substrate 2.
Accordingly, the color filter substrates 2 formed on the second mother substrate 30 are formed isolated by a dummy region 31 corresponding to the protruded portion of the thin film transistor array substrates 1 formed on the first mother substrate 20.
The unit liquid crystal display panels are suitably disposed such that the area of the first and the second mother substrates 20 and 30 can be utilized at the maximum, and though they differ depending on a model, the unit liquid crystal display panels are usually formed isolated by a dummy region 32.
After the first mother substrate 20 with the thin film transistor array substrates 1 and the second mother substrate 30 with the color filter substrates 2 are attached to each other, the liquid crystal display panels are individually cut. At this time, the dummy region 31 formed at the portion where the color filter substrates 2 of the second mother substrate are isolated and the dummy region 32 isolating the unit liquid crystal display panels are simultaneously removed.
FIG. 2 is an exemplary view showing a plane structure of the unit liquid crystal display panel.
With reference to FIG. 2, the unit liquid crystal display panel 10 includes an image display unit 13 in which liquid crystal cells are arranged in a matrix form, a gate pad part 14 for connecting gate lines (GL1 to GLm) of the image display unit 13 to a gate driver integrated circuit (not shown) to which a gate signal is applied, and a data pad part 15 for connecting data lines (DL1 to DLn) of the image display unit 13 to a data driver integrated circuit (not shown) to which image information is applied.
The gate pad part 14 and the data pad part 15 are formed at marginal portions of the thin film transistor array substrate 1, which protrude from the short side and the long side of the thin film transistor array substrate 1 as compared to the color filter substrate 2.
Though not shown in detail on the drawing a thin film transistor for switching the liquid crystal cells is formed at each of intersectional portions of the data lines DL1 to DLn and the gate lines GL1 to GLm. The data and gate lines define pixel or cell regions that include a pixel electrode connected to the thin film transistor for applying an electric field to the liquid crystal cells. A passivation film for protecting the data lines DL1 to DLn and the gate lines GL1 to GLm, thin film transistors and electrodes is over the thin film transistor array substrate 1.
The color filter substrate 2 includes color filters which are separated from adjacent cell regions by a black matrix. The color filter substrate also includes a common electrode, which is a counter electrode of the pixel electrode formed on the thin film transistor array substrate 1.
A cell gap is prepared between the thin film transistor array substrate 1 and the color filter substrate 2 that they are isolated with a certain space therebetween. The thin film transistor array substrate 1 and the color filter substrate 2 are attached by a sealant (not shown) formed at an exterior of the image display unit 13, and a liquid crystal layer (not shown) is formed in the space between the thin film transistor array substrate 1 and the color filter substrate 2.
FIG. 3 is a flow chart of a process for fabricating the unit liquid crystal display panel.
As shown in FIG. 3, the process for fabricating the unit liquid crystal display panel includes fabricating the thin film transistor array substrates on the first mother substrate and the color filter substrates on the second mother substrate (P1); attaching the first mother substrate and the second substrate with a certain space maintained therebetween (P2); cutting the first mother substrate and the second mother substrate as attached and extracting unit liquid crystal display panels (P3); and checking the unit liquid crystal display panels (P4).
As illustrated in the flow chart of FIG. 4 the step (P3) for cutting the first and second mother substrates and extracting unit liquid crystal display panels includes: loading the first and second mother substrates (S1); cutting the loaded first and second mother substrates into unit liquid crystal display panels (S2); checking a cut section of the unit liquid crystal display panel (S3); grinding a marginal portion of the unit liquid crystal display panel and cleaning it (S4); and unloading the unit liquid crystal display panel (S5).
As shown in FIG. 5, thin film transistor array substrates 111 are formed on the first mother substrate 110, and color filter substrates 121 are formed on the second mother substrate 120.
The thin film transistor array substrates 111 or the color filter substrates 121 may be randomly defective due to an unexpected flaw during any of the fabrication processes. The defective cases are shown by ‘NG (No Good)’ in the drawing, while ‘G (Good)’ indicates that there is no defect.
After the first mother substrate 110 and the second mother substrate 120 are attached, they are cut into the unit liquid crystal display panels.
Then, ‘G’-indicated thin film transistor array substrate 111 and ‘G’-indicated color filter substrate 121 may be attached and cut into a unit liquid crystal display panel, ‘NG’-indicated thin film transistor array substrate 111 and ‘G’-indicated color filter substrate 121 may be attached and cut into a unit liquid crystal display panel, or ‘G’-indicated thin film transistor array substrate 111 and ‘NG’-indicated color filter substrate 121 may be attached and cut into a unit liquid crystal display panel.
Among them, the unit liquid crystal display panel made from the attachment of the ‘NG’-indicated thin film transistor array substrate 111 and ‘G’-indicated color filter substrate 121 or the unit liquid crystal display panel made from the attachment of the G'-indicated thin film transistor array substrate 111 and ‘NG’-indicated color filter substrate 121 should be discarded because it contains a defect and, therefore, it should not be used in a product.
Recent efforts to increase the number of liquid crystal display panels fabricated on the mother substrates by enlarging the mother substrate cause more unit liquid crystal display panels to be defective and thus discarded. The result is that the unit liquid crystal display panels to be discarded may be subjected to a grinding, cleaning and final checking just like the good (not defective) unit liquid crystal display panels to be used in products.
That is, in the related art, the unit liquid crystal display panels to be discarded and the unit liquid crystal display panels to be products undergo the grinding and cleaning and are classified into unit liquid crystal display panels to be discarded and unit liquid crystal display panels to be products only through the final checking. Therefore, since even the unit liquid crystal display panels to be discarded are subjected to the grinding, cleaning and final checking, problems arise in that materials are wasted and a yield is degraded.
FIG. 6 is an exemplary view showing a plurality of liquid crystal display panels formed on a large scale mother substrate.
As shown in FIG. 6, six liquid crystal display panels 210 are formed isolated at regular intervals in consideration of the sizes of the mother substrate 200 and the liquid crystal display panels 210.
Meanwhile, as shown in FIG. 7, if large sized liquid crystal display panels 220 are desired to be fabricated from a mother substrate 20 is fixed in size, only three liquid crystal display panels 220 can be formed on the mother substrate 200, and the portions of the mother substrate 200 in regions where the liquid crystal display panels 220 are not formed should be discarded.
Thus, the use efficiency of the mother substrate 200 is deteriorated, resulting in a degradation of a productivity and increase in a unit cost of a product.